1. Field of the Invention
The present invention relates to a technology for distributing and controlling a token corresponding to a contraction bandwidth between a plurality of stations.
2. Description of the Related Art
A bandwidth control apparatus that controls a packet communication speed (bandwidth) to a plurality of receiver terminals is installed at a conventional relay station for a packet communication (see, for example, Japanese Patent Application Laid-Open No. H10-247944). In general, a bandwidth control is performed using a token (right of transmission) in the bandwidth control apparatus.
A bandwidth control apparatus installed in a repeater station performs a packet communication according to a contracted bandwidth by assigning an amount of token to be supplied per unit time according to a contracted content with a user (for example, a maximum downlink capacity of 100 Megabits per second (Mbps)), calculating a residual amount of token by subtracting an amount of token corresponding to a size of a transmission-permitted packet from the assigned amount of token each time a packet transmission to the user is permitted, and prohibiting the packet transmission (bandwidth control) at a point when the residual amount of token becomes “zero”.
However, with the conventional technology described above, there has been a problem that a token assigned to each station according to a contracted bandwidth cannot be effectively used in a packet communication with a plurality of stations for which the same user has a bandwidth contract.
For example, in the case where a station B (for example, YY Branch of XX, Inc.) having a 10 Mbps contract is in a standby for a packet output or a packet discard is performed because a residual amount of token for the station B is “zero” while a good packet transmission is performed for a station A (for example, Headquarter of XX, Inc.) having a 100 Mbps contract because there is a sufficient residual amount of token, a user cannot effectively use the token for the station A with a sufficient residual amount as the token for the station B, in spite that the YY Branch of XX, Inc. and the Headquarter of XX, Inc. are the same user.